Short scientific article	UDK 594.35:591.9(262.32)
Received: 2012-10-26
NEW RECORDINGS OF OPISTHOBRANCH MOLLUSKS (MOLLUSCA: OPISTHOBRANCHIA) IN THE SLOVENIAN PORTION OF THE
ADRIATIC SEA
Lovrenc LIPEJ & Borut MAVRIČ Marine Biology Station, National Institute of Biology, SI-6330 Piran, Fornace 41, Slovenia
E-mail: Lipej@mbss.org
Sašo MOŠKON
Harfa Sea d.o.o, SI-6000 Koper, Čevljarska 8, Slovenia
ABSTRACT
Four opisthobranch species have been recorded in Slovenian coastal waters for the very first time: Tylodina perversa, Janolus cristatus, Eubranchus tricolor and Dicata odhneri. The first three were to some extent expected. D. odhneri was found on two occasions, representing new data on this rather rare and less known nudibranch species. The total number of recorded opisthobranch gastropod species is now 70.
Key words: Gastropoda, Opisthobranchia, new records, Slovenia, northern Adriatic
NUOVE SEGNALAZIONI DI MOLLUSCHI OPISTOBRANCHI (MOLLUSCA: OPISTHOBRANCHIA) NELLA PARTE SLOVENA DEL MARE ADRIATICO
SINTESI
Quattro specie di molluschi opistobranchi sono state segnalate per la prima volta per le acque costiere della Slovenia: Tylodina perversa, Janolus cristatus, Eubranchus tricolor e Dicata odhneri. La presenza delle prime tre specie era in qualche modo prevista. La quarta specie, D. odhneri, piuttosto rara e poco conosciuta, e stata trovata in sole due occasioni. Il numero totale di specie di gasteropodi opistobranchi rinvenute nelíarea sale cos/ a 70.
Parole chiave: Gastropoda, Opisthobranchia, nuove segnalazioni, Slovenia, Adriatico settentrionale
INTRODUCTION
Over course of the recent decade, some scientific papers were published concerning opistobranch mollusc species in the marine waters off Slovenia's coast. The most comprehensive work was published by Turk (2000), who listed the species of Opisthobranchia from the Adriatic Sea with particular focus on the portion controlled by Slovenia. He found 23 opisthobranch species in Slovenian waters. Later the same author (Turk, 2005) published a paper on a rare and less known Cu-mannotus beaumonti in the Punta Madona protected marine area in the waters off Piran. In 2008, Lipej and colleagues (Lipej et al., 2008) presented a checklist based on significant new data, complementing the checklist of Turk (2000).
During an ongoing research of cryptobenthic microhabitats in the Slovenian sea, certain opisthobranch mol-lusks that have apparently not been recorded in the area were sighted and photographed. The aim of this paper is therefore to present records of four as yet undocumented species in the Slovenian waters of the Gulf of Trieste.
MATERIAL AND METHODS
The four opisthobranch species were recorded at linear transects by means of occasional samplings in determined localities of the Slovenian coastal sea. Special
Fig. 1: Localities where opisthobranchs were found in the Slovenian sea: • - Eubranchus tricolor, ▲ - Janolus cristatus, □ - Tylodina perversa, x - Dicata odhneri. Sl. 1: Lokalitete, na katerih so bili najdeni zaškrgarji v slovenskem morju: • - Eubranchus tricolor, ▲ - Janolus cristatus, □ - Tylodina perversa, x - Dicata odhneri.
attention was given to particular habitats and microhabitats where the specimens were recorded. All specimens were photographed and subsequently identified with the aid of identification keys and monographs such as Barletta (1980), Schmekel & Portmann (1982) and Trainito (2005).
RESULTS AND DISCUSSION
NOTASPIDEA
Family Tylodinidae Tylodina perversa (Gmelin, 1791)
A specimen of T. perversa was found in the locality of Pirancek at the entrance to the town of Piran at the depth of 7.8 m on 8th July 2012 (Figs. 1, 2d). The specimen was recorded in the muddy habitat occurring at the edge of the rocky seabed. The species was easily recognized due to its typical umbrella-like shell. Its known distribution is in the Mediterranean Sea and northeast Atlantic Ocean at least as far as the British Isles. T. perversa feeds on the Aplysina aerophoba sponge. However, according to Becerro et al. (2003) the slug could also possibly feed also on the cyanobacteria that are present in high concentrations in the ectosome of the sponge. They found that the slugs actively choose sponges with a high concentration of cyanobacteria.
NUDIBRANCHIA
Family Proctonotidae Janolus cristatus (Delle Chiaje, 1841)
One specimen of Janolus cristatus was found at a depth of 9 m at 30 June 2012 on the remains of an old car close to the tourist resort Bernardin (Figs, 1, 2c). The prevalent habitat type in the area is mud. Turk (2000) mentioned this species for the locality of Selca in Kvar-ner region, but otherwise it has been recorded from the Mediterranean to Norway. It is known to feed on erect bryozoans, especially Bugula and Cellaria species (Pic-ton & Morrow, 2010).
Family Eubranchidae Eubranchus tricolor Forbes, 1838
A specimen of E. tricolor was found on a sandy environment under the oceanographic buoy Vida on 16th March 2012 in waters off Piran. Two specimens were recorded on 23rd March 2012 at the locality of Pirancek in the precoralligeneous habitat at 8 m (Figs. 1, 2a), and another one at the same location at a depth of 6 m. Turk (2000) found this species in the Kvarner region, close to the town of Sv. Juraj. E. tricolor is a boreal species, preferring lower temperatures and is known in the North-East Atlantic Ocean, from the Arctic to France. It is known to graze on both calyptoblastic and gymno-blastic hydroids and according to Rivers & Harris (1976) the preferred prey are species of the genus Tubularia.
Fig. 2/Sl. 2: (a) E. tricolor, (b) D. odhneri, (c) J. cristatus, (d) T. perversa. (Photo/Foto: B. Mavric: 2a, 2b, 2d; S. Moškon: 2c)
Family Favorinidae Dicata odhneri Schmekel, 1967
The first specimen of Dicata odhneri was found on algal turf at the locality of Salinera on 4th September 2009 at a depth of 3m. The second specimen was found at the locality of Mesečev zaliv on 12th July 2010 at 3.5 m (Figs. 1, 2b) in the biocoenosis of photophilic algae. The species is determined by its typical white colour and yellow rhinophores.
Opisthobranch fauna of Slovenia
Altogether, with the four new recorded seaslugs the checklist of opisthobranch fauna of Slovenia is enlarged to 70 species. Three of them were expected since they have previously been found in other parts of the Mediterranean Sea while D. odhneri has since its description
in 1967 only been found in a few areas such as Gulf of Naples and in Atlantic waters of Baleal in Portugal (Silva, 2005) and Ireland (Picton & Morrow, 2010). However, since there are some additional unpublished records in other areas, the species is probably less rare than it appears to be.
Knowledge of the opisthobranch fauna of the Slovenian coastal sea will be certainly enlarged in the future. In fact, better inspection of the sampling area using new approaches together with the increased research effort could contribute to additional new findings for the area. The species list could be also enlarged by the arrival of southern thermophilous species and non-indigenous seaslugs.
NOVI PODATKI O POLŽIH ZAŠKRGARJIH (MOLLUSCA: OPISTHOBRANCHIA) V SLOVENSKEM DELU JADRANSKEGA MORJA
Lovrenc LIPEJ & Borut MAVRIČ Morska biološka postaja, Nacionalni inštitut za biologijo, SI-6330 Piran, Fornače 41 E-mail: lipej@mbss.org
Sašo MOŠKON
Harpha Sea, d.o.o. Koper, SI-6000 Koper, Čevljarska 8
POVZETEK
Avtorji poročajo o štirih vrstah polžev zaškrgarjev (Opisthobranchia), ki so bili prvič najdeni v slovenskem morju. To so: Tylodina perversa, Janolus cristatus, Eubranchus tricolor in Dicata odhneri. Prve tri vrste so bile pričakovane, saj so bile potrjene v drugih bližnjih predelih. Vrsta D. odhneri je bila doslej najdena le na manjšem številu lokalitet, zato sta dva zapisa o pojavljanju te vrste v slovenskem morju nov doprinos k poznavanju te redke in manj znane vrste. Skupaj z novimi vrstami je sedaj število ugotovljenih vrst polžev zaškrgarjev v favni Slovenije 70.
Ključne besede: Gastropoda, Opisthobranchia, novi podatki, Slovenija, severni Jadran
REFERENCES
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